Cytoplasmic incompatibility is being studied for the eradication of mosquitoes by the sterile (incompatible) male method. Culex pipiens and members of the Aedes scutellaris group are being used. We think that incompatibility is caused by infectious agents (Wolbachia or viruses) and are studying the mechanism. The relationship of the infectious agents (symbionts) to their hosts are being studied. A strain which produces few or no females is being produced for mass rearing purposes. Formal genetics of the above mosquitoes are also being studied.